Formation of transition metal oxide coatings on substrates by chemical vapor deposition is known. For example, U.S. Pat. No. 3,914,515 describes depositing semi-transparent films of transition metal oxides, in particular iron oxide and nickel oxide, by contacting a cyclopentadienyl metal compound, such as dicyclopentadienyl iron, with a heated glass substrate. "Thin Film Processes", 1978, pages 258-331, edited by J. L. Vossen and W. Kern and published by Academic Press, New York, describes formation of thin films chemical vapor deposition (CVD). Metal oxide films are discussed on pages 290-297. Such metal oxide coatings are reported to be useful in photomasks, insulators, semiconductors, and transparent conductors, and as protective coatings for high temperature materials.
Very recently, certain mixed metal oxides which are superconductors at temperatures up to the boiling point of liquid nitrogen (77.degree. K., or -196.degree. C.) or slightly above, have been discovered. For example, M. K. Wu, et al., Phys. Rev. Lett. 58, 908 (1987) and D. W. Murphy, et al., Phys. Rev. Lett. 58, 1988 (1987). In general, these new materials may be represented by the formula EQU A.sub.2 BCu.sub.3 O.sub.W
where A is a Group IIA metal of the group consisting of calcium, strontium and barium, B is a Group IIIB metal, and w is from 6.5 to 8. Superconductors have the potential for revolutionizing microelectronics and electric power transmission and making practical certain devices (such as magnetic levitation devices) that are impractical at present. While superconductors and methods for their synthesis so far have very serious drawbacks, the field appears to offer great promise as new mixed metal oxide compositions and new methods of synthesis are discovered.
Chemical vapor deposition has been extensively described in the literature (including patents) as a technique for depositing metals, alloys and certain metal compounds. While the technique has been described with reference to most transition metals and to certain other metals and metalloids (silicon, for example), commercial use of CVD for the most part has been confined to deposition of a few metals and metal compounds, such as silicon, tungsten, and certain III-V and certain II-VI compounds (denoting, respectively, a compound of a Group III metal and a Group V element, and a compound of a Group II metal and a Group VI element). The absence of suitable heat decomposable organometallic compounds for elements other than those mentioned above appears to have limited the extension of CVD to the deposition of other metals or compounds.